1. Field of the Invention
The present invention relates to a stapler which uses staples to bind the papers that are to be bound, and more particularly to a stapler which uses a drive means such as a motor.
2. Description of the Prior Art
In the past, staplers have been equipped with a striking block for driving the stable into the paper to be bound, where this striking block is moved up and down by a coupling rod which is connected to the driving means, such as a motor. With the descent of the striking block the staple penetrates the papers, and when it reaches the bottom dead point the bending of the staple is completed. Next, the striking block rises, and when it reaches the top dead point the rotation of the motor is stopped.
This type of stapler has a cylindrical cam attached to the lateral surface of the main frame and a micro-switch, or read switch, attached to the same surface, where intermittence of the electric current supplied to the drive source is performed by these switches. Further, a plurality of springs are attached to the outside of the main frame, and when the fulcrum shaft provided on the coupling rod receives an excessive load in the upward direction, it becomes possible for the fulcrum shaft to move upward in opposition to the downward pushing force of the springs. Further, the drive motor, gear train, drive gears, coupling rod, fulcrum shaft and striking block etc. are not attached to the main frame as a single unit, but rather the main frame is divided into a several parts. For this reason, the assembling operation for the stapler is inefficient, and there is also the problem of high cost due to the large number of parts.
Furthermore, the staple case which contains the staples is positioned so as to be received on one step portion formed on the staple case sidewall, or it is positioned by providing a positioning pin and hole near the fastening screw, for positioning the part intervals. Further, the tip of the striking blade, which actually strikes the binding staple and drives it into the papers, is formed with a flate surface. For this reason, there is the problem of the staple being dislocated from the staple striking blade, making it impossible to drive the staple in properly.
There is also the problem that in case the strike could not be completed during the operation of the striking block and it stopped halfway through, it was necessary to perform manual switching of the polarity of the electric current in order to raise the striking block and remove the material which is to be bound.